40°, 50° and 90°
the sum of the angles in a triangle = 180°
sum the parts of the ratio : 4 + 5 + 9 = 18 parts
divide 180 by 18 to obtain 1 part
[tex]\frac{180}{18}[/tex] = 10° ← 1 part
4 parts = 4 × 10 = 40°
5 parts = 5 × 10 = 50°
9 parts = 9 × 10 = 90°
